Glucocorticoids are an important part of treatment in severe anterior, intermediate, posterior, and panuveitis. A major problem with present drug therapy is the inability to achieve adequate intraocular drug concentration. In particular, uveitis is well known for its long duration due in part to the difficulties associated with poor intraocular penetration of topical medications into the posterior segment (Bloch-Michel E. (1992). “Opening address: intermediate uveitis,” In Intermediate Uveitis, Dev Ophthalmol. W. R. F. Boke et al. eds., Basel: Karger, 23:1-2; Pinar, V. Intermediate uveitis. Massachusetts Eye & Ear Infirmary Immunology Service; Rao, N. A. et al. (1997). “Intraocular inflammation and uveitis”, In Basic and Clinical Science Course. Section 9 (1997-1998) San Francisco: American Academy of Ophthalmology, pp. 57-80, 102-103, 152-156; Boke, W. (1992). “Clinical picture of intermediate uveitis,” In Intermediate Uveitis, Dev Ophthalmol. W. R. F. Böke et al. eds., Basel: Karger, 23:20-7; Cheng C-K et al. (1995). “Intravitreal sustained-release dexamethasone device in the treatment of experimental uveitis,” Invest Ophthalmol Vis Sci. 36:442-53). Systemic glucocorticoid administration may require prolonged exposure of high plasma concentrations (administration of 1 mg/kg/day for 2-3 weeks) so that therapeutic levels can be achieved in the eye (Pinar, V. “Intermediate uveitis,” Massachusetts Eye & Ear Infirmary Immunology Service. These high drug plasma levels often lead to systemic side effects such as hypertension, hyperglycemia, increased susceptibility to infection, peptic ulcers, psychosis, and other complications (Cheng C-K et al. (1995). “Intravitreal sustained-release dexamethasone device in the treatment of experimental uveitis,” Invest Ophthalmol Vis Sci. 36:442-53; Schwartz, B. (1966). “The response of ocular pressure to corticosteroids,” Ophthalmol Clin North Am 6:929-89; Skalka, H. W. et al. (1980). “Effect of corticosteroids on cataract formation,” Arch Ophthalmol 98:1773-7; Renfro, L. et al. (1992). “Ocular effects of topical and systemic steroids,” Dermatologic Clinics 10:505-12). In addition, overall drug delivery to the eye may be poor due to the short drug plasma half-life limiting exposure into intraocular tissues. The most efficient way of delivering drug to the posterior segment is to place it directly in the vitreous (Maurice, D. M. (1983). “Micropharmaceutics of the eye,” Ocular Inflammation Ther 1:97-102; Lee, V. H. L. et al. (1989). “Drug delivery to the posterior segment” Chapter 25 In Retina. T. E. Ogden and A. P. Schachat eds., St. Louis: CV Mosby, Vol. 1, pp. 483-98; Olsen, T. W. et al. (1995). “Human scleral permeability: effects of age, cryotherapy, transscleral diode laser, and surgical thinning,” Invest Ophthalmol Vis Sci 36:1893-1903). Intravitreal injections have shown promising results, however, due to the short intraocular half-life of glucocorticoids (approximately 3 hours), intravitreal injections must be repeated to maintain drug levels which increases the potential for side effects such as retinal detachment, endophthalmitis, and cataract (Maurice, D. M. (1983). “Micropharmaceutics of the eye,” Ocular Inflammation Ther 1:97-102; Olsen, T. W. et al. (1995). “Human scleral permeability: effects of age, cryotherapy, transscleral diode laser, and surgical thinning,” Invest Ophthalmol Vis Sci 36:1893-1903; Kwak, H. W. and D'Amico, D. J. (1992). “Evaluation of the retinal toxicity and pharmacokinetics of dexamethasone after intravitreal injection,” Arch Ophthalmol 110:259-66). Topical, systemic, and periocular glucocorticoid treatment must be monitored closely due to toxicity and the long-term side effects associated with chronic systemic drug exposure sequelae (Rao, N. A. et al. (1997). “Intraocular inflammation and uveitis”, In Basic and Clinical Science Course. Section 9 (1997-1998) San Francisco: American Academy of Ophthalmology, pp. 57-80, 102-103, 152-156; Schwartz, B. (1966). “The response of ocular pressure to corticosteroids,” Ophthalmol Clin North Am 6:929-89; Skalka, H. W. and Pichal, J. T. (1980). “Effect of corticosteroids on cataract formation,” Arch Ophthalmol 98:1773-7; Renfro, L and Snow, J. S. (1992). “Ocular effects of topical and systemic steroids,” Dermatologic Clinics 10:505-12; Bodor, N. et al. (1992). “A comparison of intraocular pressure elevating activity of loteprednol etabonate and dexamethasone in rabbits,” Current Eye Research 11:525-30).
U.S. Pat. No. 5,501,856 discloses controlled-release pharmaceutical preparations for intraocular implants to be applied to the interior of the eye after a surgical operation for disorders in retina/vitreous body or for glaucoma.
U.S. Pat. No. 5,869,079 discloses combinations of hydrophilic and hydrophobic entities in a biodegradable sustained release implant, and describes a polylactic acid polyglycolic acid (PLGA) copolymer implant comprising dexamethasone. As shown by in vitro testing of the drug release kinetics, the 100-120 μg 50/50 PLGA/dexamethasone implant disclosed did not show appreciable drug release until the beginning of the fourth week.
U.S. Pat. No. 5,824,072 discloses implants for introduction into a suprachoroidal space or an avascular region of the eye, and describes a methylcellulose implant comprising dexamethasone.
U.S. Pat. Nos. 4,997,652 and 5,164,188 disclose biodegradable ocular implants comprising microencapsulated drugs, and describes implanting microcapsules comprising hydrocortisone succinate into the posterior segment of the eye.
U.S. Pat. No. 5,164,188 discloses encapsulated agents for introduction into the suprachoroid of the eye, and describes placing microcapsules and plaques comprising hydrocortisone into the pars plana.
U.S. Pat. Nos. 5,443,505 and 5,766,242 discloses implants comprising active agents for introduction into a suprachoroidal space or an avascular region of the eye, and describes placing microcapsules and plaques comprising hydrocortisone into the pars plana.
Zhou et al. disclose a multiple-drug implant comprising 5-fluorouridine, triamcinolone, and human recombinant tissue plasminogen activator for intraocular management of proliferative vitreoretinopathy (PVR) (Zhou, T, et al. (1998). “Development of a multiple-drug delivery implant for intraocular management of proliferative vitreoretinopathy,” Journal of Controlled Release 55: 281-295.)
There is a continued need for efficacious intraocular sustained release drug therapies for patients with inflammatory conditions.
All references cited herein are hereby incorporated by reference in their entirety.